Technical Abstract:
Phaseolus vulgaris (common bean) is one of the most important grain legumes for direct human consumption. It comprises 50% of the grain legumes consumed worldwide and is important as a primary source of dietary protein in developing countries. Legumes form a unique symbiotic relationship with rhizobium that allows the fixation of atmospheric nitrogen in the plant nodules. The advent of RNAseq technology allows us to identify all expressed transcripts in tissues of interest. In this work we present the first whole transcriptome study of nodulation and SNF in Phaseolus vulgaris. We have sequenced common bean RNA samples isolated from nitrogen-fixing nodules, from non-fixing nodules-–elicited by an inefficient rhizobium mutant strain (fix-)--and from the roots associated with the nodules. A total of seven RNA samples were collected at two distinct stages of nodule development: 5 and 21 days post inoculation. A sample of non-inoculated roots was used as a control. The RNAseq data generated from these samples was used in a de-novo gene assembly, generating a total of 199,469 predicted non-redundant transcripts. Comparative analyses of the expression profile of these genes has allowed the identification of genes specific for nodulation, nitrogen fixation, and changes induced in root tissues due to SNF. Our findings of the P. vulgaris nodulation and SNF whole transcriptome may be applicable to other legumes.